Recovery of copper from scrap materials and liquids is assuming increased importance because of the need to maximize copper production due to increased needs for this metal.
Recovery of copper by cementation is an old procedure wherein copper in solutions such as mine waters and leach liquors is precipitated out of solution by the use of metallic iron. The basic cementation reaction is: EQU CuSO.sub.4 +Fe .fwdarw. Cu+FeSO.sub.4
However, in this reaction some of the ferrous sulfate becomes oxidized to ferric sulfate which results in redissolving of some of the copper to form a copper sulfate as illustrated in the following formula: EQU Cu+Fe.sub.2 (SO.sub.4).sub.3 .fwdarw. CuSO.sub.4 +2 FeSO.sub.4
The result is a lower recovery of copper and an increased loss of iron.
Another method of recovering copper is from solid scrap materials where it has been used to clad other metals as in certain bearings and wires. While a great deal of the copper can be separated from such materials by physical means, as by grinding, not all of the copper can be removed. This raises a dual problem, particularly in copper clad iron materials since an appreciable amount of copper is lost and the iron can then not be used again because the copper would contaminate the iron or steel product being formed from such scrap. Such copper clad iron scrap is, therefore, simply slagged. If the copper could be substantially completely removed, the resultant iron scrap could be recycled for use in iron and steel making operations.